The document describes several types of megalithic monuments found in Ireland dating back to 3200 BC, including portal dolmens, court cairns, and passage tombs. It focuses on the passage tombs of Newgrange, Knowth, and Dowth located in the Boyne Valley area of Ireland, which have elaborate decorations and were built with astronomical alignments, such as allowing sunlight to enter the tombs at the winter solstice. The passage tombs have corbelled roofs and were used as burial chambers for cremated remains, with some stones decorated with spiral and abstract patterns.

1. The Boyne Valley 3200 BC

3. Diagram-Court Cairn Creevykeel, Co. Sligo Semi-circular forecourt made up of upright stones Gallery surrounded by oval-shaped cairn or mound of stones without any roof

5. Passage Graves The most impressive remains of the late Stone Age are the deep and mysterious stone passage graves. Set into the ground above the river Boyne in a loop as it meanders on its final stretch across the plains of Co. Meath are the finest of these graves, Newgrange and its two satellites, Knowth and Dowth.

6. It is almost certain that these patterns have an astronomical connection, but they may also have had a religious meaning or may have been a form of primitive calendar. Knowth

7. Dowth

9. Newgrange Within these graves we find Ireland’s earliest examples of human artwork in the form of ornamented stones.

10. Here we find evidence of a highly organised society which used concentric whirls, circles and abstract repeating patterns, the meaning of which we can only speculate about. The roof Box may have been a form of primitive calendar.

13. There is an opening over the roofbox which allows the sun to shine through during the Winter Solstice

15. WINTER SOLSTICE 21 ST DECEMBER Shortest day of the year

16. ENTRANCE STONE 3 left handed spirals 4 right handed spirals

18. 22 standing stones on the left 21 standing stones on the right side The Passage at Newgrange is 19 metres long Narrow stream of light shines directly through roof box along passage.

19. The famous Triple Spiral on the end recess of the chamber The wonderfully decorated ceiling in the east recess of the chamber Many of these stones are decorated The spirals on the stone of the west recess

21. The first part of the passage is roofed by 3 large slabs After this the roof is CORBELLED

22. CORBEL VAULT View looking up towards the roof Side View The stones gradually slope inwards and finish with one large stone or cap on the chamber roof on the outside

24. The outer edges of the corbels are sloped downwards so that rain water drains off and onto the cairn. This method is shown to be effective in that the passage and chamber at Newgrange remain dry to this day.

25. Corbelled stones in the roof Details of patterns found on the corbel stones in the roof of the chamber

28. Entrance Stone Nobody knows the meaning of these concentric spirals The vertical line separating the circles appears to be significant

29. Kerbstone 52 Even more pronounced is the vertical line on kerbstone 52, which is the other richly decorated stone

31. Kerbstone 52 is at the back of the mound and lines up directly with the entrance stone